Tuesday, October 4, 2011
Cerebral ischemia is the reduction or loss of oxygen to the cerebral tissue due to poor or lack of blood circulation. When ischemia lasts more than three or five minutes, it causes the death of neurons (nerve cells) since they do not receive oxygen. The death of brain tissue is called cerebral infarction. When a small artery in the brain gets occluded (blocked), it causes focal cerebral ischemia, which reduces blood flow to a specific brain area, increasing the risk of cell death to that particular region; it can be either caused by thrombosis or embolism. When the total blood flow to the brain is stopped, it causes global cerebral ischemia, which is usually caused by cardiac arrest. If sufficient circulation is restored within a short period of time, symptoms may be transient. Nevertheless, if a significant amount of time goes by before restoration, brain damage may be permanent due to nerve cells death.